Resolution and Quality Issues in 3D Analysis of Inscribed Signs: An Example from Cypro-Minoan Inscriptions

A recurrent demand in many archaeological digital documentation systems is the need for an accurate as possible registration of data. Somehow, contrary to this request, are efforts led by various computer science groups dealing with 3D documentation and focusing on developing fast and cheap solutions to record 3D models of archaeological assets. The aim of the article is to highlight the importance of aligning the 3D documentation strategy to the archaeological aims, by detailing all factors to be considered when deciding on one documentation strategy over another. The archaeological question discussed here, part of the PhD thesis of one of the co-authors (MP), relates to the Cypro-Minoan signatory and its diachronic variability. The 3D geometric characterization of signs and subsequent shape analysis is the method chosen to reach this goal. A major effort to be invested in correctly determining the shape and variability of each sign, is in assuring that the 3D captured shape is as close as possible to the archaeological reality, which is a common problem not only in palaeographical analysis but also in other fields, where features of interest are in the sub-millimetre range. The paper will illustrate how different data acquisition approaches and post-processing steps such as alignment methods and error treatment may distort the visualised result and thus have a negative impact on planned analysis. Thus, it will argue for the importance of more detailed paradata to allow an informed assessment of the reliability of 3D models and it proposes a list of values and decision-making steps that help make the 3D digitization process more robust and verifiable.

Vybrané metody 3D digitalizace aplikované na příkladech hodinových exemplářů Náchodského muzea

The aim of the article is to present the possibilities of the digitization of 3D objects using both professional and publicly accessible methods. The article also aims to focus on selected tools of 3D digitization and their possible use in the memory institutions, such as museum, libraries and archives.

3D Surveying of Underground Built Heritage: Opportunities and Challenges of Mobile Technologies

Among the existing Cultural Heritage settings, Underground Built Heritage (UBH) represents a peculiar case. The scarce or lack of knowledge and documentation of these spaces frequently limits their proper management, exploitation, and valorization. When mapping these environments for documentation purposes, the primary need is to achieve a complete, reliable, and adequate representation of the built spaces and their geometry. Terrestrial laser scanners were widely employed for this task, although the procedure is generally time-consuming and often lacks color information. Mobile Mapping Systems (MMSs) are nowadays fascinating and promising technologies for mapping underground structures, speeding up acquisition times. In this paper, mapping experiences (with two commercial tools and an in-house prototype) in UBH settings are presented, testing the different handheld mobile solutions to guarantee an accurate and reliable 3D digitization. Tests were performed in the selected case study of Camerano Caves (Italy), characterized by volumetric complexity, poor lighting conditions, and difficult accessibility. The aim of this research activity is not only to show the differences in the technological instruments used for 3D surveying, but rather to argue over the pros and cons of the systems, providing the community with best practices and rules for 3D data collection with handheld mobile systems. The experiments deliver promising results when compared with TLS data.

Research on key technology of 3D digitization for secondary system of power grid based on model application analysis

In order to solve the problems of long development time, poor expansibility and small application scope in the digital design of secondary system of intelligent substation at present, this paper puts forward the 3D assembly techniques based on the expanded model by analyzing the integration of secondary model files of intelligent substation. In the design process of this method, the relationship between primary equipment and secondary equipment, the mapping between logical circuit and real circuit are fully considered. By using standard family library techniques, file analysis techniques and automatic mapping techniques, the coupling between physical model and logical relationship is realized. Taking the actual 220kV intelligent substation as the pilot, the three-dimensional model in secondary system simulation analysis, online monitoring and the application of fault diagnosis shows that the techniques can effectively improve the efficiency of three-dimensional design and maintenance of secondary system.

INTEGRATION OF PHOTOGRAMMETRY, COMPUTED TOMOGRAPHY AND ENDOSCOPY FOR GYROSCOPE 3D DIGITIZATION

Cultural heritage preservation via 3D digitization is becoming more and more important. Besides conventional buildings and landmarks, many technical instruments and artifacts, which belong to tech heritage (TH), are also of great importance, historically and didactically. Gyroscopes, which can be dated back for 200 years, are fascinating instruments with complex structures and different working principles. With such properties, any 3D digitization of Gyroscopes could not be realized by simply using conventional solutions of photogrammetry or laser scanning. In our work, we introduce photogrammetry, endoscopy and computed tomography (CT) for an integrated 3D digitization solution. Though photogrammetry has been widely used for the purpose of cultural heritage preservation, 3D reconstructions using the other two sensor systems have their own challenges. For an endoscope, a pre-calibration solution has been put forward and the Structure-from-Motion (SfM) process has been optimized to deal with the drift caused by a long imaging trajectory. Regarding the CT 3D reconstruction, we mainly focus on the 3D representation’s completeness and the denoising process. In the section of data integration, we designed different methods according to the characteristics of the objects as well as the 3D models from different sonsors. In case of limited overlap between the pair of point clouds, the Gauss-Helmert model with manually picked control points is applied for the estimation of the transformation matrix. CT point clouds, which hold only the intensity values representing the material attenuation, could be integrated with photogrammetry data via a surface color mapping method using the photogrammetric images or the primitive based corresponding virtual control points. Through our research, the concept of integrating photogrammetry, endoscopy and CT for 3D digitization of Gyroscopes is validated. Furthermore, advantages and disadvantages involved in the complete process are discussed and a solid foundation has been laid for further research.

Virtual Equivalents of Real Objects (VEROs): A type of non-fungible token (NFT) that can help fund the 3D digitization of natural history collections

Describing a substantial proportion of the world’s species could be made much easier by the 3D digitization of collections, which would facilitate the dissemination of taxonomic information locked up in natural history museums. Three-dimensional imaging captures many characters and allows a lot of versatility in the way that morphological data is displayed and used (Wheeler et al. 2012; Faulwetter et al. 2013). Moreover, the loss and damage of valuable specimens, many of which are very fragile, can be reduced as a result of the use and sharing of 3D model substitutes among researchers. This can also lead to a reduction in the handling and transportation expenses of many specimens.

3D Reproductions of Cultural Heritage Artifacts: Evaluation of Significance and Experience

3D digitization of cultural heritage has long been used to preserve information about cultural heritage (CH) objects such as architecture, art, and artifacts. 3D dissemination of CH objects through technologies such as augmented reality, virtual reality, and 3D printing have impacted the fields of art history and cultural heritage and have become more common. Yet, studies that go beyond the technical aspects of 3D technology and treat such topics as their significance for restoration, conservation, engagement, education, research, and ethics hardly exist. The aim of this paper is twofold: on the one hand, it aims to get a better understanding of the applicability of each technology for different purposes (education, research, conservation/restoration, and museum presentation), and, on the other hand, it focuses on the perception of these technologies. This research was carried out by combining a literature review with quantitative and qualitative analyses of the data acquired through (1) a questionnaire of eleven questions and (2) a workshop with a group of specialists and non-specialists who were asked to brainstorm about the different uses of the 3D technologies and their applicability to their areas of work and research. Based on the analysis of these quantitative and qualitative data, we provide some criteria for using 3D digitized and printed reproductions to enhance cultural experiences. The results demonstrate the importance of carefully designing 3D interactions in the personal and cultural contexts of end-users and cultural institutions in order to create authentic cultural experiences.

A practitioner’s guide to fringe projection profilometry

Many techniques exist for 3D digitization of cultural heritage objects. Paintings, manuscripts, and other near-planar objects are especially challenging to digitize because of their minute surface variations. Of the existing techniques, fringe projection profilometry (FPP) is one of the most promising approaches for measuring the surface shape of such objects. In practical implementations of FPP, one needs to understand and control various sources of error due to system hardware and environmental conditions. It is difficult to find information on this in one place in the literature, which discourages application of the technique. In this paper we present a practitioner’s guide to phase-shifting fringe projection profilometry that covers critical but often omitted implementation details required for successful application of the technique.